1. Field of the Invention
This invention relates to an improved composite power generator and more particularly, to a feed technique of coal to a gasification furnace in a coal gasification composite power generator of a pressurized entrained bed type.
2. Description of the Prior Art
Typical coal feed systems adapted for use in known coal gasification furnaces are shown in FIGS. 2 and 3. The system shown in FIG. 2 is an aqueous slurry system in which coal from a coal bunker 1 is milled in a wet mill 2 and is then fed to a gasification furnace 4 by means of a pump 3. Water 5 and a surface active agent 6 are fed to the mill 2.
The system shown in FIG. 3 is a dried, finely powdered or pulverized coal feed system. In this system, coal fed from a coal bunker 11 is finely powdered in a pulverizer 12. The finely powdered coal is fed to a cyclone 19 as entrained with a drying gas 18 which is being fed from a fan 17 to the pulverizer 12. The drying gas 18 is produced in a hot air furnace 13 in which a fuel 14 is combusted with the aid of air 15 and is passed through a cooler 16 to the fan 17.
The coal collected in the cyclone 19 and a bag filter 20 is stored in a coal bottle 21, followed by passing through a pair of lock hoppers 22a, 22b to a gasification furnace 23. Reference numeral 10 denotes a vent pipe through which a gas containing steam is discharged in the air and which is connected to a smokestack. The combustible gas produced in the gasification furnace 23 is used as energy for power generation.
However, the above prior art systems have the following problems. With the aqueous system shown in FIG. 2, a large amount of moisture is brought into the gasification furnace, so that the heat energy in the gasification furnace is lost corresponding to latent heat for evaporation of water, thus leading to a lowering of the formation efficiency of the combustible gas.
On the other hand, the dried, finely powdered coal feed system shown in FIG. 3 undesirably needs a separate hot air furnace for providing a drying medium. This requires an additional fuel for the hot air furnace.